1. Technical Field
This invention relates generally to static gaskets of the type used to establish a gas/fluid-tight seal between two members to be clamped together and to their method of construction.
2. Related Art
In establishing a gas/fluid-tight seal between two members to be clamped together, such as a cylinder head and engine block or an engine block and an exhaust manifold, it is common to use a static gasket having one or multiple layers. Generally, at least one of the layers of the multilayer gasket, sometimes referred to as an active or functional layer, has one or more seal beads to establish a gas/fluid tight seal about openings, such as cylinder bores, coolant openings, and/or bolt openings. Another of the layers, sometimes referred to as a distance layer, can be configured to abut the functional layer to facilitate setting a gap thickness which is needed to attain the desired compression ratio in a diesel engine, while also helping to establish the gas/fluid tight seal about the openings by limiting the compression of the seal beads of the functional layer.
To facilitate compressing the seal beads of the functional layers to the desired height, without over compressing the seal breads, the functional or distance layer, if provided, is typically formed having one or more raised protrusions formed within the material thereof. The raised protrusions are typically formed in a coining process via a high tonnage forming press. As such, the press plastically deforms the material of the respective layer to form the raised protrusions. Unfortunately, the high tonnage presses used to form the raised protrusions are very expensive, occupy of a large amount of space, and upon being set-up, are dedicated to a specific size and pattern of raised protrusions, thereby requiring a great deal of time and effort to change from one pattern of raised protrusions to another. Further, as a result of plastically deforming the material of the active layer or distance layer, the material properties are altered in an unpredictable manner, thereby creating, within the material of the distance layer, unpredictable material properties, which ultimately can lead to premature failure of the distance layer's ability to function as intended. Further yet, having to mechanically upset the material of the active layer or distance layer typically results in the raised protrusions having shapes and sizes deviating from one another and from the shape and size actually desired, mainly due to tolerances within the layer material, as well as tolerances of the press and tools used to form the raised protrusions. Further yet, if the protrusions are formed in an active layer, further problems commonly arise as a result of the material typically being a high strength spring steel, such as FH 301 SS, for example, which is generally difficult to plastically deform in predictable fashion.